I’m more of a tea person than a coffee person, so I find myself with a lot of used tea leaves and bags. While I know these can be composted, I was wondering if I could apply the used tea leaves directly to my citrus tree’s soil. Here’s what I found.

Tea leaves are a beneficial fertilizer for citrus trees. The leaves contain nitrogen, phosphorus, potassium, and other trace vitamins and minerals that feed and support plant and fruit development. When used as mulch or compost, they increase water retention in the soil and attract earthworms. 

So, while tea leaves are great for citrus trees, are there exceptions? Also, how do you apply tea leaves as a fertilizer? Let’s find out more.

Why Are Tea Leaves Good For Citrus Trees?

a used tea bag

Tea leaves are like most other organic matters—a good material fertilizer that can increase the nutrient content, organic matter content, and water retention of the soil around a citrus tree. 

The leaves are rich in minerals and vitamins like nitrogen, potassium, and phosphorus that support both the tree and any citrus fruits it will produce. Tannins in tea leaves also help to acidify the soil, which citrus trees prefer due to their subtropical origins (more on pH later).

Also, these leaves attract earthworms as they forage and further enrich the soil with their waste. As a bonus, the burrowing from earthworms increases soil aeration and water flow to the tree’s roots.

What about the caffeine in tea leaves, though? Will it affect citrus trees?

Is Tea Leaf Caffeine Bad For Citrus Trees?

The caffeine in black, green, and especially white tea leaves is too low to bother citrus trees. Leaves from herbal tea are caffeine-free, so it’s not even a potential issue. If you’re concerned about the level of caffeine, you can add the tea leaves to your compost pile first to allow the caffeine to disperse.

While the amount of caffeine in coffee can harm citrus trees, know that it’s twice the caffeine of black tea, and three times that of green tea, so it’s not as much of a concern.

To avoid your citrus tree soil from getting a small dose of caffeine, you might be tempted to use the leaves from a decaffeinated tea blend, but this can do more harm than good.

Caffeine is a very persistent compound that is difficult to remove from leaves, and the process of decaffeination commonly uses harmful chemicals like Methylene Chloride or Ethyl Acetate.

While that might sound bad enough, the decaffeination process also removes many of the antioxidants and polyphenols that make tea such a great product.

Remember that caffeine levels are very low in black and green teas, hardly present in white teas, and completely absent from herbal teas.

Herbal teas still contain many of the same nutrients, vitamins, and minerals that caffeinated teas do, but in differing proportions depending on just what kind of herb they are. In any case, herbal tea leaves can safely be used as mulch or fertilizer on any plant or citrus tree without any risk of excess caffeine.

So, while caffeine won’t bother your citrus tree in small amounts, if you’re still worried, you can throw the tea leaves in the compost bin for the caffeine to break down first. Avoid using decaffeinated tea leaves if you’d like to prevent excess chemicals from being introduced into the soil.

What Are the Nutrients in Tea Leaves?

Tea leaves contain significant amounts of nitrogen, phosphorus, and potassium. These are the big three macronutrients of gardening, commonly referred to as NPK. Secondary nutrients include calcium, iron, and magnesium.

Each one of these primary nutrients does something different for the plant:

  • Nitrogen: is the main greening element—it directly fuels the growth of leaves and branches.
  • Phosphorus: supports strong root growth as well as the production of flowers and fruit—all of which is very important for citrus trees! 
  • Potassium: helps the plant to process sugars, absorb water, and activate its growth enzyme, among other functions. This makes it an important contributor to a citrus tree’s vitality overall.

Fertilizers are labeled with an NPK number, which tells you how much of each of these nutrients it contains.

The NPK of tea leaves is 4-0.4-2, which means that the leaves contain 4% nitrogen, 0.4% phosphorus, and 2% potassium.

Tea leaves also contain some other nutrients, such as:

  • Vitamins: D, K, and riboflavin.
  • Minerals: calcium, iron, magnesium, nickel, zinc, and fluoride.
  • Antioxidants: including lignans, tannins, flavonoids, and phenols. Antioxidants protect plant cells from becoming damaged.
  • Polyphenols: or micronutrients, including tannic acid, which can gradually encourage the soil around your citrus tree to acidify slightly. Again, citrus trees prefer more acidic soils because they resemble their native soils in more subtropical regions.

It can also be helpful to know that younger, fresher tea leaves have a higher nutrient content than older leaves do, but most tea leaves are picked when the leaves are young and tender, and they’re dried soon after. The exception to this is Pu-Erh teas, which are made of leaves that are harvested later.

What Is the pH of Tea Leaves?

Tea leaves also have a good amount of acidity. Their pH levels typically range from 5-7, but some sour or fruity teas can be as low as 3. This is good news for citrus trees since they prefer a slightly acidic pH of 6.0-7.0.

You can mix the tea with a little compost (which is usually slightly alkaline), and you have a well-balanced pH for your citrus tree’s soil.

However, it can be difficult to determine the pH and balance it appropriately in the soil. For this reason, consider getting a pH meter to monitor the soil. To see which pH meter I recommend, check out my recommended tools page.

So, if you’re ready to apply your used tea leaves as citrus tree fertilizer, how should you go about it?

3 Ways To Apply Tea Leaves as a Fertilizer

Tea leaves can be applied to the soil by evenly sprinkling them over the surface around the base of the tree, and then gently scratching them into the top few inches of soil. They can be dry or wet. It’s best to use organic teas and to remove any tea bag that is not 100% paper or silk.

When using tea leaves as a mulch or fertilizer, it is best to only use organic teas. Conventionally produced teas often have trace amounts of chemical pesticides, and it’s best to avoid introducing these into your garden

If your tea leaves are inside of a tea bag, you should cut the bag open and take the tea leaves out of it.

Unless a tea bag is specifically stated by the purveyor to be made of 100% paper or silk, it probably is all or partly made of polyester threads, which do not decay and may leach into your soil. If the bag is silk or paper and therefore compostable, you should also remove any extra paper tags or staples.

Now, let’s get into a few of the specific methods to use tea leaves for your citrus tree’s soil.

1. Apply the Tea Leaves Directly

coffee grinds, eggshells, and tea bags to fertilize my kaffir lime tree
Coffee grinds, eggshells, and tea bags I used to fertilize my kaffir lime tree

One of the easiest ways to use tea leaves is to simply spread them over your citrus tree’s soil.

However, if the tea leaves aren’t worked into the soil, they may form a mat over the top of the soil that can block water and air from reaching the roots.

Lightly scratching them into the first 1-2 inches of soil helps incorporate them evenly so that they can decompose and release nutrients without problems.

2. Add to the Compost Bin

Tylers vermicomposting bin
My vermicompost bin at home

If you have a compost pile or vermicompost bin (which I highly recommend), tea leaves are a great addition. Earthworms love to eat tea leaves and the high level of nutrients can increase the quality of fertilization from the compost.

If you’re just adding the occasion tea leaves to your compost pile, you shouldn’t have to worry about using too much.

However, if you’re adding several tea bags a day or more, it can be good to do a quick calculation and balance out your compost pile (especially if you have a smaller pile).

A good way to do this is to use a compost calculator. For this, count the tea leaves as a high-nitrogen green matter like grass clippings or vegetable scraps, not low-nitrogen brown matter like sticks or wood chips.

3. Make Compost Tea

If you’d prefer to apply tea leaf fertilizer as a liquid, well, that’s pretty simple too. Fresh or used tea leaves can simply be dropped into a bucket or jar of water and allowed to steep for a few days (yes, we’re basically giving the tea a second life here).

You could even do a “sun tea” method by putting the leaves in a large glass jar, filling it with water, and then letting it sit in the sunlight until the water is deeply colored. 

Then, pour the tea out evenly around the citrus tree about 1.5 feet away from the trunk (which is the zone where the tree’s main uptake roots live).

Alternatively, you can make a hot tea solution by boiling water, pouring it over the tea leaves, and letting them steep for anywhere from an hour up to two days. 

When using this method, it is very important to let the tea cool completely before watering the tree with them, as hot water can scald the root tissue.

Of course, if you do make tea for your citrus tree, you can strain out the leaves or just pour them out with the water and work them into the soil afterward.

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